HEAT-TRANSFER BEHAVIOR OF REINER-RIVLIN FLUIDS IN RECTANGULAR DUCTS

Numerical studies are reported for the fully developed heat transfer b ehavior of elastic non-Newtonian fluids in steady laminar flow through rectangular ducts. The Reiner-Rivlin formulation with finite values o f the second normal stress coefficient is used to model the flow. The limiting case of zero secondary normal stress difference corresponds t o a purely viscous power-law fluid. Finite difference methods are deve loped to obtain the heat transfer results for the H2 thermal boundary condition for different combinations of heated and adiabatic walls. Th e influence of the second normal stress coefficient, the Reynolds numb er, the Peclet Number and the aspect ratio on the heat transfer are co nsidered. It is found that the secondary flow, which is associated wit h the presence of second normal stresses, results in a significance in crease in the heat transfer, especially for aspect ratios of 0.5 and 1 .0. The general behavior of the Nusselt number predicted for the Reine r-Rivlin fluid is found to be in good agreement with experimental resu lts reported for viscoelastic fluids.